battery has voltage but inadequate amperage?

Is it possible for a car battery to have adequate voltage (head lights
comes on etc, but car won't start). The other day I wasn't able to
start my car (You can hear a click but starter won't turn over). So I

towed it to the mechanic and left it there. He said my battery is no
good and replaced the battery for me. Anyway he explained that it had
voltage but failed the load test. What is involved in the load test?
Is it something you can do on my own in the future? What kind of
equipment do I need? I have a autoranging digital multimeter if that
will help.

Yes. YOur battery could have the right voltage but lack amps.
Voltage is a function of the Pb to PbS to Pb chemical reaction.
Amps are a function of plate area.
A load test involves putting a known load on the battery and watching
the voltage and/or amperage draw-down vs. time.
You can do it yourself but you will have to get a battery load
testing device. They are not cheap.

When performing a load test, the tester simulates a starter draw on the
battery.
Sounds like you have considered building a load tester.
One needs to understand you get what you pay for based upon price. The
cheap nichrome wire resistance can be bought as inexpensive as $15 on
internet tool web sites up to $60 at NAPA. Carbon Pile testers are cost
prohibitive unless used in a fleet. There is a Motorola tester available
that combines the best of many worlds. Please search the Internet.
A load tester consists of a resistance as cheap as nichrome wire to
expensive as carbon pile discs used as a rheostat.
Besides impressing your neighbors. A home made load tester can be
constructed using sealed beam headlight bulbs. Using ohms law one can wire
the bulbs series and parallel to have an average 5 to 10 seconds desired
resistance.
Average resistance encompasses knowing starter draws for a wide range of
starters i.e. 150 amp draw for 4 cyl aluminum rice rocket engines up to 250
amp draw for older American cast iron block engines with big starter motors.
Has anyone checked the starter for amperage draw?
Has anyone checked the battery cabling for any loose connections.
A bad starter that has a flat spot can cause a misdiagnosis of a battery.

Yes, a battery can lack amps. Grounds play a big role in
got voltage, not amperage, situations. Corroded grounds will increase in
resistance, show ok with test light, but will not carry the * current *
needed to start a car. Beef up grounds and enjoy longer battery /
alternator life.

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